1. Field of the Invention
The invention relates to a device for processing a metal surface of a metal object which is in motion during the processing.
2. Description of Related Art
The U.S. Pat. No. 5,312,530 describes a surface processing device for running material. This device is provided with an inner cavity that is fed with a processing agent under pressure. A jet forming slot is used to direct a well laminar jet of the processing agent under an acute angle, 40 to 70 degrees, to the running material. The jet forming slot is rotational symmetric and surrounds the path, along which the material is passed. Further, an;electric electrode is disposed in the cavity, whereby an additional electrode is disposed, in the passage direction of the material, slightly spaced from the jet forming spot, whereby a bipolar electrolyte cell is formed. It is practical, that a plurality of processing units, each having an inner cavity and a jet forming slot are arranged one after the other in the passing direction of the material. The cavity is annular and it opens towards the axial bore, through which the material to be processed runs, through an annular slot. The processing agent emerges through the slot in annular shape of such a small width that the jet acts as a knife. The electrodes enhance the cleaning effect further. If the electrode disposed with the cavity is connected to the minus pole whereas the other electrode surrounding the running material is connected to the plus pole of the rectifier then the surface to be processed becomes anodic under the narrow jet of the processing agent. Thereby, the resistive layer of solved contaminants and metal ions surrounding the running material will be dissolved and permits a higher current to pass through the cell.
When using an annular slot as in the referred U.S. Pat. No. 5,312,530 segments of the jets from the opposed directions weaken each other so that the total effect to agitate the surface of the object is not as strong as the sum effect of the segments of the jets individually could be.
The object of the present invention is to eliminate some of the drawbacks of the prior art and to achieve a new and more viable device for processing a metal surface of a metal object which is in motion during the processing so that the processing agent is fed by jets to the surface of the metal object. The essential novel features of the invention are apparent from the appended claims.
According to the invention the processing agent is directed by jets to the surface of the metal object being in motion through nozzles which are positioned to each other so that part of the surface to be processed is under processing in one position of directing processing agent. In one position of directing processing agent to the surface to be processed there is at least one nozzle through which a jet of the processing agent is directed to the surface so that at most 70 per cent of the surface to be processed is under direct influence of the jets. The jet emerges from a hole of the nozzle having maximum width less than 8 times of the width of the surface. In the device of the invention there are at least two positions of directing processing agent to the surface to be processed within a distance to each other so that essentially the whole surface to be processed is at least once under the jets of the processing agent in that time when the surface of the metal object is going through the device of the invention.
In the device of the invention there is at least one reservoir which is filled with processing agent. The processing agent is a medium for coating, electrolytic cleaning or plating which are most suitable treatments to be processed by means of the device of the invention. The reservoir is provided with an inlet in one wall and with an outlet in another wall opposite to the first wall. The inlet and the outlet are used to direct the metal object to be processed in motion of high speed up to 20 to 40 m/s through the reservoir in case of coating. In plating the typical speeds are from 5 to 40 m/s.
The metal object to be processed is in the device of the invention in the interaction between the processing agent and the metal surface. In order to minimise the so called diffusion layer on the metal surface, the metal object is treated by a strong agitation or mixing of the processing agent in a very close vicinity of the metal surface. A turbulence which will minimise the diffusion layer, is partly caused by the metal object itself which is in motion through the reservoir of the processing agent. In order to increase turbulence in the vicinity of the metal surface, in the reservoir there are installed in at least two positions at least one nozzle in each position to direct jets of the processing agent against the metal surface.
When using the device of the invention the consecutive positions of directing jets are advantageously so operated that the directions of the jets are different. Therefore, the metal surface is processed in each position of directing jets so that advantageously the same part of the metal surface is not processed in two consecutive positions. The consecutive positions of directing jets can also be in separate reservoirs.
The jet from one position can be directed so that the direction of the jet is essentially perpendicular to the metal surface. The direction of the jet can also be such that the jet forms an acute or obtuse angle with the moving direction of the metal surface to be processed. The directions of the jets even in the consecutive positions can be different; one can have direction in acute angle and the other in an obtuse angle. The directions of the jets formed in the same position can be different depending on the surface to be processed.